EP3624415A1

EP3624415A1 - A decentralized asset custody and clearing platform system

Info

Publication number: EP3624415A1
Application number: EP19184783.9A
Authority: EP
Inventors: Jianhua Ju; Fulin Tang; Yuqi LIN; Boli WANG
Original assignee: Blue Helix
Current assignee: Blue Helix
Priority date: 2018-09-11
Filing date: 2019-07-05
Publication date: 2020-03-18
Anticipated expiration: 2039-07-05
Also published as: ES2893608T3; EP3624415B1; US10521861B1; CN109308658A

Abstract

The invention relates to an efficient threshold distributed elliptic curve key generation and signature method, which includes : 1) all n nodes generate their own key pair (ptki, puki) separately without the participation of a trusted center, where ptki is the private key and puki is the public key; 2) each node processes its own public-private key pair according to the secret sharing protocol, and completes the conversion of the (n, n) threshold to the (t, n) threshold; 3) after determining t signature nodes, each node generates a (t, t) threshold private key according to the threshold logic, and completes the mapping of ptki to ptki'; 4) according to the signature logic, each node uses ptki' to complete the communication and calculation in the signature protocol, and stores the relevant calculation results, and finally completes the overall signature. The invention realizes centerless, strong robust and high security and reduces transaction fees. The invention relates to an efficient threshold distributed elliptic curve key generation and signature system.

Description

TECHNOLOGY FIELD

This invention involves blockchain field; particularly it involves the construction of a decentralized asset custody and clearing platform and trading platform. It proposes an efficient and secure solution for constructing a decentralized asset custody and clearing platform.

BACKGROUND TECHNOLOGY

Blockchain is a chained data structure that is connecting data blocks in chronological order, and it is a distributed ledger that is immutable and unforgeable guaranteed by cryptography, where the ledger records digital asset derived from cryptography. All in all, blockchain technology is a whole new distributed infrastructure and compute mode that utilizes chained-block data structure to authenticate and store data, that utilizes distributed nodes consensus algorithm to generate and update data, that utilizes cryptography to protect data transmission and access, that utilizes smart contracts which are formed by automated scripts to program and process data.
Centralized exchange is a centralized platform or application, which allows users to trade fiat currencies or cryptocurrencies with cryptocurrencies. Users directly deposit cryptocurrencies into exchange, which helps store capital as a wallet until orders generated. Centralized exchanges are with high efficiency and good user experiences, while they suffer from crucial defects such as low security.
Decentralized exchange is differentiated from centralized exchange that assets of decentralized exchange users are not controlled by a single institution or platform. In the whole life cycle of a transaction, user assets are under full control by users themselves or decentralized communities or organizations. Decentralized exchanges are robust to security attacks, while they suffer from bad user experiences and low trading efficiencies.
More specifically, a decentralized exchange uses blockchain technology which, in order to be suitably secure, requires the use of a large, distributed network of nodes. A trading event starts with a first 'block' being broadcast to all nodes in the network. This block contains a digital signature, timestamp and relevant information relating to the trading event. In order to 'verify' the block, a so-called mining process is undertaken within the distributed network, wherein the first block is tested by a number of available nodes according to the specific rules/incentives associated with the exchange and, if enough (i.e. a majority of) nodes agree that the block carries a valid transaction, they add a new block to the chain, which is again timestamped. The chain is then tested by a number of (different) available nodes and, once again, if enough (i.e. a majority of) nodes agree that the block carries a valid transaction, they add a new block to the chain. This process may be repeated many times, depending (amongst other thing) on the degree of security required, wherein, in theory, the more iterations of the verification (i.e. the longer the blockchain), the greater will be the robustness of the exchange to security attacks.
However, a significant drawback associates with the use of a mining process to verify and complete a transaction is that it takes a long time, often several days which, in turn, leads to the above-mentioned bad user experiences and low trading efficiencies.

INVENTION CONTENTS

In order to tackle the issues of bad user experiences and low trading efficiencies, this invention is targeted to provide a construction method for a decentralized asset custody and clearing platform which maintains the user experience and trading efficiency to that of a centralized exchange, while keeps the high security and attack-robust features of a decentralized exchange. In accordance with a first aspect of the present invention there is provided a computer-implemented decentralized digital asset storage and transfer system, comprising a first access gateway communicably coupled to a platform comprising at least three dedicated and computationally independent computing nodes, wherein said platform is configured to, upon receipt of a digital asset storage or transfer instruction via said first access gateway, perform a method comprising:

performing, by each said node independently, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result thereof to the other nodes;
determining a consensus between verification results determined by said nodes; and
in the event of a consensus, each node processing said instruction, independently of said other nodes.

Thus, by providing at least three dedicated and computationally independent computing nodes, communicably coupled to the first access gateway, a verification process similar to that described above in relation to each step or phase of a blockchain process can be realized, except that the required number of available nodes is always available to perform the verification process substantially simultaneously and the 'voting' result can be returned very quickly. Thus, the speed and efficiency of a centralized digital asset storage and transfer system can be retained, whilst the robustness of a decentralized system can be provided.
In one exemplary embodiment of the present invention, the method may further comprise packing result data from said processing by each node into respective block data, and adding said block data to a local blockchain network hosted by said platform. Optionally, the platform may be configured to define a said node as an originating node and others of said nodes as verifying nodes, and wherein the platform may be further configured to, upon receipt of a digital asset storage or transfer instruction, perform a method which may comprise:

performing, by said originating node, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result to said verifying nodes;
upon receipt of the verification result from said originating node, performing by each said verifying node a verification process in respect of said instruction, and broadcasting the result thereof to each of the other nodes;

determining a consensus between the verification results determined by said nodes; and
in the event of a consensus, each node processing said instruction independently of said other nodes.

In one exemplary embodiment, in the event that a said consensus between the verification results of said nodes is not reached, the platform may be configured to select an alternative one of said nodes as an originating node, and may repeat the said method with the other nodes as verifying nodes.
Optionally, said originating node may be defined according to a mining validation strategy. In an exemplary embodiment, said originating node may be configured to perform said verification process in respect of said instruction to obtain a first clearing result, sign said first clearing result with its private key, and may broadcast the signed first clearing result to said verifying nodes.
In an exemplary embodiment of the invention, the verifying nodes may be configured to, upon receipt of said signed first clearing result, perform said verification process in respect of said instruction to obtain a local clearing result, and may compare said local clearing result with said first clearing result to determine a verification result.
Optionally, each said verifying node may be configured to sign the respective verification result with its own private key and may broadcast the signed verification result to the other nodes.
According to an exemplary embodiment of the invention, each node may be configured to, upon receipt of signed verification results from the other nodes, calculate, using said verification results, a final verification result.
Optionally, each node may be configured to perform a verification process in respect of said first clearing result in relation to a respective final verification result and, if said clearing result is verified, may pack said first clearing result and verification data into block data and add said block data to a local blockchain network hosted by said platform.
In an exemplary embodiment of the invention, a consensus may be determined between the verification results of processing by said nodes when the verification results of a majority of said nodes correspond.
Optionally, asset control rights may be stored in a distributed manner among said nodes, each node storing a fragment of a respective asset control right.
In an exemplary embodiment of the invention, the system may further comprise a second access gateway configured to be coupled to an external blockchain network.
This aspect can further improve the robustness of the system against security attacks, but the mining process subsequently performed by the external blockchain network to validate a transaction can be significantly shortened (i.e. less blocks), relative to known decentralizes asset storage and trading systems, thereby improving trading efficiency.
Optionally, the system may further comprise a second access gateway configured to be coupled to an external blockchain network, and wherein, when said instruction comprises a digital asset transfer, said second access gateway may be configured to, in the event that a consensus is determined between the verification results of said nodes, package respective asset control right fragments into a transfer instruction compatible with a specified external blockchain network, and transmit said transfer instruction to said external blockchain network.
In accordance with a second aspect of the present invention there is provided a computer-implemented method of performing decentralized digital asset storage and transfer, comprising providing a first access gateway communicably coupled to a platform comprising at least three dedicated and computationally independent computing nodes, the method comprising:

receiving a digital asset storage or transfer instruction via said first access gateway to
performing, by each said node independently, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result thereof to the other nodes;
determining a consensus between verification results determined by said nodes; and
in the event of a consensus, processing said instruction by each node independently of said other nodes.

As such, solutions of the present invention provide an efficient and secure decentralized asset custody and clearing platform system. The platform receives trading and custody instructions through the access gateway. Each of the nodes operates transactions clearing and assets custody independently. The result of each node's clearing and custody operations is broadcast to other nodes. After the nodes reach consensus on the results, they complete the decentralized asset clearing and custody instructions together.
When the decentralized asset custody and clearing platform performs transaction clearing, the nodes collectively perform clearing on the transaction, which specifically includes the following steps:

Step 1: According to a certain strategy, the originating node of the transaction clearing is selected from the N nodes, and the other N-1 nodes are the verifying nodes of the transaction clearing. The selection strategy of the originating node includes but is not limited to the following: POW (proof of work), POS (proof of stake), DPOS (delegated proof of work), and simple polling alternation.
Step2: The originating node performs clearing of M (M>=1) transaction instructions in unit time t, and obtains a clearing result R. R can be expressed formally as: R = ϕ(t, M), where ϕ denotes the agreed clearing method. The originating node signs the clearing result R using the private key si representing its own identity, obtains the Rsi, and then broadcasts it to the other N-1 verifying nodes.
Step 3:After receiving the clearing result Rsi broadcasted by the initiating node, any verification node performs the clearing of the M transaction instructions again to obtain the local clearing result r. The verification node compares r with R to obtain the verification result f of this time. f can be expressed formally as: f = λ(r, R), λ represents the agreed verification method. The verification node signs the verification result f with the private key sv representing its own identity, obtains fsv, and then broadcasts it to all other nodes.
Step 4: Any node obtains the verification result f of all other N-1 nodes regarding the clearing result R. Based on N fs, all nodes locally calculate the final verification result F. F can be expressed as: F = ψ (f1, f2...fn), ψ denotes the agreed final verification method, which is generally calculated by the method of majority results.
Step 5: Any node performs corresponding processing on the clearing result Rsi according to F: if F is passed, then {Rsi,t,m} is packed into block data, and the data is added to the local chain by adding a block. The chain structure finally forms a transaction clearing blockchain through repeated data addition; if F is not passed, replace the initiating node according to the strategy described in step 1, and re-execute step1-5 to clear the m trading instructions..

When the decentralized asset custody and clearing platform performs asset custody, the N nodes collectively manage the custody assets, and specifically include the following steps:

Step1: Fragment the asset control right P and distribute the asset control rights fragments in the N nodes. P can be formally described as: P = ω (p1, p2 ... pn), ω represents fragmentation processing method, in the multi-signature scheme, p represents a private key of n private keys; in a single signature scheme, p represents A 1/n private key fragment.
Step 2: In order to prevent the control rights of the assets are completely lost when a few nodes in N nodes fail, each node performs redundant storage of asset control rights fragments according to the control strategy. The redundant storage scheme needs to satisfy the majority of nodes could recover the control right of the assets, while a few nodes can not recover the control right.
Step 3: The asset control right fragment of each node is protected by the threshold logic to ensure that only after the withdrawal instruction passes the above-mentioned clearing process and is written in the blockchain, it can be accessed by the node.
Step4: When a majority of the N nodes agree on the withdrawal instruction, the blockchain gateway packages the multiple asset control rights fragments into an acceptable transfer instruction of the blockchain in which the custody asset is located, and broadcasts to the blockchain network.

The decentralized asset custody and clearing platform interacts with external systems through an access gateway. External systems, such as brokers or exchanges, issue accounts opening, transfer, withdrawals, and trading orders to the decentralized asset custody and clearing platform through the access gateway. When platform receives the account opening and withdrawal request, it adopts a multi-factor authentication method. After confirming the user request again, the corresponding operation is completed. If the user performs an asset withdraw operation, after the clearing and threshold logic of the decentralized asset custody platform is sequentially performed, the request is sent to the corresponding blockchain network to complete the final withdraw operation according to the type of the asset extraction requested by the user.
The multi-factor authentication is one or a combination of short message, mail, and GA authentication.
Beneficial effects of this invention include but are not limited to: 1) Constructs an asset custody and clearing platform that is not relying on any single institution or entity, by decentralized and multi-node organizational forms. User assets security is determined by majority nodes combined, instead of any single or a few nodes on the platform. This essentially solves the security issue of centralized exchanges; 2) The decentralized exchanges and virtual brokers constructed on such platform could provide users with similar performance and user experience to that of centralized exchanges, while maintaining independent operations and sharing market depth and liquidity; 3) The operations by virtual brokers, exchanges, decentralized asset custody and clearing platform are all trackable, queriable, immutable. This prevents the inventive for these parties to inflate fake assets from underlying mechanism and well tracks liabilities in case of disputes.

BRIEF DESCRIPTION OF THE FIGURES

The invention is more fully appreciated in connection with the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a method for constructing an efficient and secure decentralized asset custody and clearing platform system according to the present invention.
FIG. 2 is a flow diagram of the asset custody service according to the present invention.
FIG. 3 is a flow diagram of an external system account opening and asset withdraw according to the present invention.
FIG. 4 is a flow diagram of an external system transaction order according to the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A schematic diagram of the overall architecture of an efficient and secure decentralized asset custody and clearing platform is shown in Figure 1. As illustrated, the system comprises a first access gateway communicably coupled to a platform. The platform comprises at least three dedicated, computationally independent computing nodes, denoted clearing/verifying and clearing/initiating nodes in Figure 1. The account opening, transfer, withdrawal and ordering instructions of the external system are routed to the decentralized asset custody and clearing platform system via the access gateway routing. As shown in FIG.1, node 2 is designated the transaction clearing initiation node, and the remaining nodes are transaction clearing verification nodes. When a transaction is initiated, Node 2 clears the transaction record 1-M in time t, and broadcasts the clearing result to other N-1 nodes for verification. After receiving the clearing result of the originating node (Node 2 in Figure 1), each verification node re-clears the transaction record 1-M, compares the clearing result with the received clearing result, obtains the verification result, and broadcasts the verification result to other N-1 nodes. If N/2 or more nodes (i.e. a majority) determine that the clearing result is correct, then the clearing result is verified, and the transaction 1-M will be packaged into blocks, and added to the unchangeable block record in an additional manner to become a part of the local blockchain. If N/2 or more nodes think that the clearing result is wrong, then the clearing result is not verified, and node 3 will replace node 2 as the initiating node, re-clear the transaction 1-M, and follow the preset penalty policy to penalize node 2. If the transaction is a withdrawal instruction, the above-described verification process is first performed in respect of the instruction. If the instruction is verified, a withdrawal request is sent to the threshold logic on the basis of the clearing result. The threshold logic distributes the request to each node, and each node votes for the withdrawal request through its own asset control right fragment. Once again, if more than N/2 nodes agree to the withdrawal, the withdrawal request is passed. If N/2 or more nodes disagree with the withdrawal, the withdrawal request is rejected.
The process of asset custody service is shown in FIG.2. After the process starts, the decentralized asset custody and clearing platform first judges whether the custody asset is correctly received. If it is not received, then the process ends abnormally. After receiving the asset, the asset control right is first fragmented. Then, control right fragment is redundantly backed up according to the security policy.
The platform is coupled, via a second access gateway (Figure 1), to an external blockchain network (e.g. BTC, ETH, EOS, etc.) which may support external brokers or exchanges. The external system's account opening and asset withdraw process is shown in Figure 3. After the process starts, the broker first verifies the identity of the user, and if the verification fails, the process ends abnormally. After the verification is passed, the decentralized asset custody and clearing platform according to an exemplary embodiment of the invention performs multi-factor verification as described above. If the verification fails, the process ends abnormally. After the verification is passed, different processes are executed according to the operation type: if it is an asset withdraw operation, the decentralized asset custody and clearing platform performs multi-node verification as described above. If the verification is passed, the asset withdraw request is sent to the corresponding (external) blockchain network to complete the asset withdraw operation. If the account opening operation is performed, the asset custody service flow is executed. After the process ends, the account opening operation ends normally.
The transaction order flow of the external system is shown in Figure 4. The external system is based on brokers and exchanges. After the process starts, the broker first judges whether the transaction instruction is received, and if there is no instruction, the process ends; after receiving the transaction instruction, the broker first signs the transaction instruction with his private key, and then sends the signed instruction to the decentralized asset custody and clearing platform according to an exemplary embodiment of the invention. After receiving the transaction instruction, the platform first detects whether the instruction includes the broker's signature, and if it does not, the platform ignores the instruction; if it does, the platform uses its own private key to sign the transaction, and then sends the transaction to the exchange; after the exchange completes the transaction order, the exchange sends the result to the decentralized asset custody and clearing platform, which completes the clearing of the transaction accordingly. Then proceed to the next transaction instruction in the same process until no new instructions are received. It will be apparent that the use of the decentralized digital asset storage and transfer system, either alone (for use in some institutions), or in conjunction with an external broker/exchange can systematically improve the efficiency and speed at which instructions can be completed, without compromising the robustness against security attacks.
The foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; obviously, many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications; they thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. Notably, not every benefit described here- in need be realized by each embodiment of the invention; rather any specific embodiment can provide one or more of the advantages discussed above. It is intended that the following claims and their equivalents define the scope of the invention.

Claims

A computer-implemented decentralized digital asset storage and transfer system, comprising a first access gateway communicably coupled to a platform comprising at least three dedicated and computationally independent computing nodes, wherein said platform is configured to, upon receipt of a digital asset storage or transfer instruction via said first access gateway, perform a method comprising:
• performing, by each said node independently, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result thereof to the other nodes;

• determining a consensus between verification results determined by said nodes; and

• in the event of a consensus, each node processing said instruction, independently of said other nodes.
A decentralized digital asset storage and transfer system according to claim 1, wherein said method further comprises packing result data from said processing by each node into respective block data, and adding said block data to a local blockchain network hosted by said platform.
A decentralized digital asset storage and transfer system according to claim 1 or claim 2, wherein said platform is configured to define a said node as an originating node and others of said nodes as verifying nodes, and wherein the platform is further configured to, upon receipt of a digital asset storage or transfer instruction, perform a method comprising:
• performing, by said originating node, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result to said verifying nodes;

• upon receipt of the verification result from said originating node, performing by each said verifying node a verification process in respect of said instruction, and broadcasting the result thereof to each of the other nodes;

• determining a consensus between the verification results determined by said nodes; and

• in the event of a consensus, each node processing said instruction independently of said other nodes.
A decentralized digital asset storage and transfer system according to claim 3, wherein, in the event that a said consensus between the verification results of said nodes is not reached, the platform is configured to select an alternative one of said nodes as an originating node, and repeat the said method with the other nodes as verifying nodes.
A decentralized digital asset storage and transfer system according to claim 3 or claim 4, wherein said originating node is defined according to a mining validation strategy.
A decentralized digital asset storage and transfer system according to any of claims 3 to 5, wherein said originating node is configured to perform said verification process in respect of said instruction to obtain a first clearing result, sign said first clearing result with its private key, and broadcast the signed first clearing result to said verifying nodes.
A decentralized digital asset storage and transfer system according to claim 6, wherein the verifying nodes are configured to, upon receipt of said signed first clearing result, perform said verification process in respect of said instruction to obtain a local clearing result, and compare said local clearing result with said first clearing result to determine a verification result.
A decentralized digital asset storage and transfer system according to claim 7, wherein each said verifying node is configured to sign the respective verification result with its own private key and broadcast the signed verification result to the other nodes.
A decentralized digital asset storage and transfer system according to claim 7 or claim 8, wherein each node is configured to, upon receipt of signed verification results from the other nodes, calculate, using said verification results, a final verification result.
A decentralized digital asset storage and transfer system according to any of claims 7 to 9, wherein each node is configured to perform a verification process in respect of said first clearing result in relation to a respective final verification result and, if said clearing result is verified, pack said first clearing result and verification data into block data and add said block data to a local blockchain network hosted by said platform.
A decentralized digital asset storage and transfer system according to any of the preceding claims, wherein a consensus is determined between the verification results of processing by said nodes when the verification results of a majority of said nodes correspond.
A decentralized digital asset storage and transfer system according to any of the preceding claims, wherein asset control rights are stored in a distributed manner among said nodes, each node storing a fragment of a respective asset control right.
A decentralized digital asset storage and transfer system according to any of the preceding claims, further comprising a second access gateway configured to be coupled to an external blockchain network.
A decentralized digital asset storage and transfer system according to 12, further comprising a second access gateway configured to be coupled to an external blockchain network, and wherein, when said instruction comprises a digital asset transfer, said second access gateway is configured to, in the event that a consensus is determined between the verification results of said nodes, package respective asset control right fragments into a transfer instruction compatible with a specified external blockchain network, and transmit said transfer instruction to said external blockchain network.
A computer-implemented method of performing decentralized digital asset storage and transfer, comprising providing a first access gateway communicably coupled to a platform comprising at least three dedicated and computationally independent computing nodes, the method comprising:
• receiving a digital asset storage or transfer instruction via said first access gateway to

• performing, by each said node independently, a verification process in respect of said instruction to determine a verification result, and broadcasting said verification result thereof to the other nodes;

• determining a consensus between verification results determined by said nodes; and

• in the event of a consensus, processing said instruction by each node independently of said other nodes.